The FDA today updated its safety review of the smoking cessation drug varenicline (Chantix, Pfizer). A large meta-analysis, which the FDA had required Pfizer to perform, found a higher rate of major adverse cardiovascular events (MACE) in patients taking varenicline than in patients taking placebo. However, the increase in risk was very small and did not achieve statistical significance. The FDA concluded that “it is uncertain whether the excess risk for the Chantix group was due to the drug or due to chance.”

The FDA said the results of the meta-analysis are consistent with findings of an earlier trial described in a previous FDA communication. The new meta-analysis utilizes data from 7,002 patients who were randomized to placebo or varenicline in one of 15 double-blind trials.

The FDA reported a low MACE rate for both groups. Although varenicline-treated patients had nearly double the risk of an event as the placebo-treated patients, there was a wide range in the confidence interval. The FDA noted that cardiovascular mortality and all-cause mortality was slightly lower in the varenicline-treated group, though the difference was of course not statistically significant.